The present invention relates to a portable trimmer for cutting weeds or the like, and, in particular, to a safety cover for a cutting blade of a portable trimmer.
Portable trimmers for cutting weeds or the like have been known. A conventional and typical portable trimmer includes an engine, for example, a compact air-cooled type two-stroke cycle internal combustion engine, a supporting tube which has a power transmitting shaft inserted therein and extending straight from the engine in a forward direction, and a cutting blade which is mounted on the supporting tube at a front end thereof and is rotatably driven by the engine. A safety cover for covering a rear side of the cutting blade (an operator side) is mounted on such a type of portable trimmer at the front end of the supporting tube in accordance with the safety standard for preventing the operator from being wounded by a stone or the like scattered by the rotating blade. The safety cover for covering the cutting blade (hereafter, the xe2x80x9ccutting blade safety coverxe2x80x9d) generally comprises a roof plate portion extending radially outward along and above a rotational plane of the cutting blade, and a skirt portion extending downward from an outer circumferential edge of the roof plate portion to the rotational plane.
There are several kinds of cutting blades, for example, a metal disc-type cutting blade with a plurality of cutting edges formed on a circumference thereof, and a nylon cord. The disc-type cutting blade and the nylon cord are different from each other in the radius of a rotational plane thereof. In case of the disc-type cutting blade, there are various types of cutting blades of different radii. Further, since the disc-type cutting blade and the nylon cord are different in the structure for mounting them to the front end of the supporting tube. They are also different in the vertical distance between a mounting position of the safety cover with respect to the supporting tube and the rotational plane of the cutting blade.
The cutting blade safety cover with optimal dimensions may preferably be selected in response to the type or size of the cutting blade since grass or the like is likely to be caught between an edge of the cutting blade and an inner circumference of the skirt portion when there is an excessively wide clearance therebetween and it is impossible to cut the grass short when the skirt portion for covering the cutting blade is too long. Therefore, when the cutting blade is replaced, the cutting blade safety cover must also be replaced with one having a dimension suitable thereto.
Conventionally, there has been a cutting blade safety cover devised so as to be capable of corresponding to various cutting blades. For example, U.S. Pat. No. 4,864,728 discloses a cutting blade safety cover suitable for various cutting blades having different mounting heights. This cutting blade safety cover has a flexible structure in which the vertical length of the skirt portion can be varied corresponding to a varied height position of a cutting blade mounted thereto. The cutting blade safety cover is structured to be divided circumferentially along a middle portion of the skirt portion in the vertical direction thereof so that the length of the skirt portion can be varied by allowing the skirt portion to be mounted to the roof plate portion with two different height positions.
In a conventional cutting blade safety cover described above, although the length of the skirt portion can be varied, an entire cutting blade safety cover must be replaced when a cutting blade of a different radius is employed.
Further, since generally being made by plastic injection molding, the cutting blade safety cover is preferably shaped to be easily released from the molding dies.
Accordingly, at least one advantage of the present invention is to provide a cutting blade safety cover that can be easily replaced by suitable one with optimal shape in response to the kind of the cutting blade.
A further advantage of the present invention is to provide a cutting blade safety cover that can be easily injection-molded.
The initial advantage of the present invention described above can be achieved by a cutting blade safety cover for covering a rear portion of a cutting blade of a portable trimmer, the safety cover comprising, a roof plate portion and a skirt portion suspended there from the roof plate portion, the roof plate portion being separated at a radially middle location thereof into a radially inner portion and a radially outer portion, the radially inner portion and the radially outer portion being detachably attached to each other so that the radially outer portion is replaceable with another radially outer portion having a dimension suitable for covering a cutting blade of a different dimension.
According to the present invention, the cutting blade safety cover is separated at a radially middle location of the roof plate portion of the cutting blade safety cover so that the radially outer portion of the cutting blade safety cover is detachable from the radially inner portion. Various types of radially outer portions having various radial dimensions and various vertical dimensions of the skirt portions corresponding to various cutting blades are prepared in advance. A replacing operation of the cutting blade can be easily carried out since only the radially outer portion needs to be replaced with a new one having a suitable size.